Internal combustion engines are often equipped with a piston pump in a fuel supply system. The piston pump may feed fuel from a reservoir to a fuel injection valve. The piston pump usually includes a push rod adapted to make a reciprocating movement within a chamber, a stopper for concentrically receiving the push rod, and a sealing ring disposed between the push rod and the stopper. The stopper is also utilized for limiting a downward movement of the push rod. In particular, the stopper may be disposed at a bottom of a housing of the piston pump, and may limit the downward movement of the push rod, when a bottom surface of the push rod comes into contact with a top surface of the stopper.
Further, the fuel is usually accumulated in the chamber, and is moved by the reciprocating movement of the push rod. For example, when the push rod is moving towards the top surface of the stopper, the fuel available in the chamber gets pressurized between the push rod and the stopper. As a result, pressure surges are created in the fuel flowing towards the sealing ring hampering the operation of the sealing ring. Generally, sealing rings are not manufactured to withstand such pressure surges of the fuel. As a result, the sealing rings fail and have to be frequently replaced. This would lead to inconvenience and expenses with regard to replacement and maintenance of the sealing ring. Moreover, after flowing past the sealing ring, the fuel may get mixed with lubrication oil resulting into a dilution of the lubrication oil. The lubrication oil may also have to be replaced once the dilution makes the lubrication oil unusable, for example, due to decrease in viscosity. The maintenance of the sealing ring and the lubrication oil may lead to a significant machine downtime and affect an overall performance of an engine.